New York — American atheists and religious “nones,” those with no affiliation with any institution of worship, have proclaimed the first Thursday of every May to be a “National Day of Reason.”

Of course, according to federal law, the first Thursday of every May is also the nation’s official National Day of Prayer, enacted by Congress in 1952 and signed by President Harry Truman to promote a day “on which the people of the United States may turn to God in prayer and meditation at churches, in groups, and as individuals.”

The secular alternative, around since 2003, is just a blip compared with its federally-sponsored rival, which President Obama officially declared on Thursday, just as every president every year has done since the law was passed. All 50 of the nation’s governors have proclaimed Thursday a day of prayer, and hundreds of the nation’s leaders attended events and acknowledged the day of prayer as well.

“We wanted a more universal alternative to the National Day of Prayer,” says Roy Speckhardt, executive director of the American Humanist Association, one of the sponsors of the national day of reason. “We wanted to provide a better alternative, something that everybody can embrace.”

And with the ranks of religious “nones” still growing at a rapid pace, secular and humanist advocates say they have begun to see a corresponding rise in interest in their ideas as well. “The concept came out several years ago now, but it’s gotten a lot more attention in the last year or two,” says Mr. Speckhardt.

Together, there are about 13 million self-described atheists and agnostics in the US, or about 6 percent of the population, and about an equal number of secular, unaffiliated “nones,” according to a 2012 survey conducted by the Pew Research Center’s Religion and Public Life Project.

But the ranks of the unaffiliated, including those who say they have their own private spirituality, have swelled 67 percent since 1990, as the young and middle-aged eschew traditional religion more and more, according to the American Religious Identification Survey.

Indeed, there are signs the “Day of Reason” is beginning to get at least a modicum of official recognition after being mostly ignored.

Rhode Island Gov. Lincoln Chafee (I) issued an official proclamation declaring May 1 as the National Day of Reason, which he also did in 2013. Denver Mayor Michael Hancock also proclaimed May 1 a national day celebrating the place of reason in the nation’s history.

Two Democratic members of Congress, Rep. Michael Honda of California and non-voting Rep. Eleanor Holmes Norton (D) of the District of Columbia have voiced support.

“Our Founding Fathers based the Constitution of the United States upon philosophical principles that have their origins in the historical Age of Reason,” said Congressman Honda in a statement entered into the congressional record. “On the National Day of Reason, we remember and celebrate this history, including the First Amendment’s guarantee of freedom of religion and freedom from the imposition of religion by the state.”

There were also a few scattered events in various communities around the country, and atheist and humanist groups scheduled blood drives, community clean ups, and other charitable activities to recognize the day.

“I think that from a humanistic perspective, we see better value in that than prayer,” says Speckhardt. “And those things are relics of our war past, from the Cold War era, and it’s time to get beyond these things.” The early May date for the National Day of Prayer was put in place by President Ronald Reagan to be a direct counterpoint to May Day workers celebrations, which were major national holidays in Communist countries at the time.

Along with the phrase “under God” in the Pledge of Allegiance, which was also added in the 1950s, official acknowledgements of a deity continue to irk many American “non-theists,” who have been waging a somewhat quixotic battle for decades to expunge these sorts of generic religious expressions, which they believe violate the First Amendment’s Establishment Clause, often interpreted as “the separation of Church and State.”

Indeed, “frustrating” is a word many use to describe their mostly-futile legal efforts to expunge these national expressions. In 2010, the Freedom From Religion Foundation sued to have the National Day of Prayer law removed, and a federal judge in Wisconsin agreed, ruling it unconstitutional. In 2011, however, a federal appeals court overturned the decision, ruling the Freedom From Religion Foundation did not have proper standing to sue.

The American Humanist Association is currently party to two pending lawsuits in Massachusetts and New Jersey, arguing to remove the phrase “under God” from the required recitation of the Pledge of Allegiance in public schools.

Critics complain, too, that the organizers of the National Day of Prayer are nearly exclusively conservative Evangelical Christians. Its Task Force is chaired by Shirley Dobson, wife of Focus on the Family founder James Dobson, and from 1991 to 2009, the National Day of Prayer Task Force was headquartered within the organization’s offices. And since 1990, nearly every one of the Day of Prayer’s Honorary Chairpersons have been conservative Evangelicals.

According to the Day of Prayer’s official site, “This government-proclaimed day is offered to all Americans, regardless of religion, to celebrate their faith through prayer. However, the efforts of the NDP Task Force are executed specifically in accordance with its Judeo-Christian beliefs.”

The Dobsons were central figures in Thursday’s official observance in Washington, D.C., hosted by Republican Congressman Robert Aderholt from Alabama.

“We’re also frustrated that our representatives, who are supposed to represent us all, are trying to push payer,” says Speckhardt, “which is a private matter and not universal by any stretch.”